Smaller Mean Values Research Articles

The association of body height, height variability and inequality.

Body height is associated with environmental conditions. It has been suggested that under poor conditions when inequality within a population increases, also the variability in height tends to increase. We studied the association of body height, within-country variability in height and geographic and historic origin in 767 growth studies carried out in 80 countries, published between 1794 and 2013, with data on N = 78,184 infants age 2 years, and N = 2,130,729 juveniles age 7 years. The studies represent almost the whole spectrum of economic diversity in human societies since the end-18(th) century. 207 studies contained data for both infants and juveniles with 50,819 subjects (age 2), and 123,078 subjects (age 7). Multiple linear regressions showed significant interactions between height, sex, historic year of the study, geographic origin, and within-study standard deviation for height with multiple R-squared = 0.527, p < 0.001, at age 2, and multiple R-squared = 0.436, p < 0.001, at age 7. Yet, the two age groups differed in respect to within-study standard deviation for height. We found a significant association between body height and within-study standard deviation for height only at age 2: tall infant populations are less variable in height (r = -0.27, p < 0.01). There was no such association in children aged 7 years. Tall children from affluent and short children from less affluent countries do not differ in the variability of body height. The data suggest that the 'environmental adversity' hypothesis for variation in growth: small mean values for height go along with large standard deviations for height, does not apply for children at age 7.

Genetic Diversity in Kodo Millet (Paspalum scrobiculatum) Relative to Culm Strength and Yield

Presence of genetic diversity is a prerequisite for genetic improvement of any crop. As lodging and associated grain loss is a problem in kodo millet, a study was undertaken to characterize and assess the diversity in kodo millet germplasm accessions for culm strength and grain yield-related traits. Principal component and cluster analyses were performed for grouping the genotypes and to identify the traits that contributed significantly to the diversity in kodo millet. Cluster analysis grouped the genotypes into four main clusters. Cluster I had highest values for most of the traits, except internode length and grain yield. Cluster IV had smallest mean values for all studied traits. The genotypes in Cluster II had highest values for grain yield and test weight. Cluster III was intermediate in performance for most of the traits, hence genotypes in Cluster I could be used for improving culm-related traits and test weight, and those in Cluster II for improving grain yield and test weight and Cluster III for improving earliness.

A long-term volume transport time series estimated by combining in situ observation and satellite altimeter data in the northern South China Sea

We deployed five pressure-recording inverted echo sounders (PIES) along a satellite altimeter track across the continental slope of the northern South China Sea (NSCS) from October 2012 to July 2014, and obtained a time series of volume transport (VT PIES ) across the sec- tion from their records. Applying the empirical relation- ship between VT PIES and the satellite altimeter sea surface height anomaly difference across the section, we obtained a time series of volume transport (VT NSCS ) over 22 years from 1992 to 2014. The VTNSCS shows a small mean value of −1.6 Sv (1 Sv = 10 6 m 3 s −1 ) (i.e., toward the south- west), but a significant seasonal reversal and mesoscale eddy induced fluctuations ( −11.8 to 19.7 Sv). The monthly mean of VTNSCS over 22 years shows a maximum (3.6 Sv) in July and a minimum (−7.3 Sv) in December. This is the first long time series of volume transport for the NSCS based on in situ data.

A Novel Multiscale Intensity Metric for Evaluation of Tropical Cyclone Intensity Forecasts

Abstract In this study, a new multiscale intensity (MSI) metric for evaluating tropical cyclone (TC) intensity forecasts is presented. The metric consists of the resolvable and observable, low-wavenumber intensity represented by the sum of amplitudes of azimuthal wavenumbers 0 and 1 for wind speed within the TC vortex at the radius of maximum wind and a stochastic residual, all determined at 10-m elevation. The residual wind speed is defined as the difference between an estimate of maximum speed and the low-wavenumber intensity. The MSI metric is compared to the standard metric that includes only the maximum speed. Using stepped-frequency microwave radiometer wind speed observations from TC aircraft reconnaissance to estimate the low-wavenumber intensity and the National Hurricane Center’s best-track (BT) intensity for the maximum wind speed estimate, it is shown that the residual intensity is well represented as a stochastic quantity with small mean, standard deviation, and absolute norm values that are within the expected uncertainty of the BT estimates. The result strongly suggests that the practical predictability of TC intensity is determined by the observable and resolvable low-wavenumber intensity within the vortex. Verification of a set of high-resolution numerical forecasts using the MSI metric demonstrates that this metric provides more informative and more realistic estimates of the intensity forecast errors. It is also shown that the maximum speed metric allows for error compensation between the low-wavenumber and residual intensities, which could lead to forecast skill overestimation and inaccurate assessment of the impact of forecast system change on the skill.

Mechanical evaluation of space closure loops in Orthodontics

This study evaluated the mechanical performance of teardrop-shaped loops and teardrop-shaped loops with helix used in orthodontic space closure. Sixty retraction loops made with 0.019" x 0.025" stainless steel (SS) and beta-titanium (BT) wires were used. They were attached to a testing machine to measure the magnitudes of the sagittal force and the load-deflection ratio necessary for 1 mm, 2 mm and 3 mm activation. The results demonstrated that the BT alloy presented significantly smaller mean values (p < 0.01) of sagittal force and load-deflection than the SS alloy. The loop with the highest mean value of sagittal force and load-deflection was the teardrop-shaped loop (p < 0.01). Differences were observed in the mean values of sagittal force and load-deflection among activations, and the highest mean value was found in the activation of 3 mm, while the smallest mean value was evident in the activation of 1 mm (p < 0.01). It could be concluded that the metallic alloy used and the presence of a helix in configuration of the loops may have a strong influence on the sagittal force produced and on the load-deflection ratio; the teardrop-shaped loops and teardrop-shaped loops with helix in BT presented the release of lighter forces; the teardrop-shaped loop in SS generated a high load-deflection ratio, providing high magnitudes of horizontal force during its deactivation.

Thickness of dentine in mesial roots of mandibular molars with different lengths

To measure the minimum thickness of the distal (furcal) root dentine associated with the buccal and lingual canals of the mesial roots of mandibular first molars with different lengths. The mesial roots of 285 mandibular first molars were allocated into three groups according to their length: group I - long (24.14 mm +/- 0.85), group II - medium (22.10 mm +/- 0.65) and group III - short (19.97 mm +/- 0.75). The minimum thickness of the distal (furcal) root dentine associated with the buccal and lingual canals of the mesial roots 2 mm below the furcation was measured. The distance between the buccal and lingual canals, and the depth of concavity in the distal surface of the mesial roots were also measured. anova and Tukey-Kramer were used to test for significant differences among the groups. The minimum thickness of the distal wall of the mesiobuccal canal was significantly different (P < 0.05) between group I (long) and III (short), with long teeth having the smallest mean values. No significant difference was found in the thickness of the distal wall of the mesiolingual canal among the groups studied (P > 0.05). The shortest distance between the mesiobuccal and the mesiolingual canals was observed in group III (P < 0.05). The distal (furcal) concavity was deeper in group I (P < 0.05) when compared with the other groups. There was a significant difference in the minimum thickness of the distal (furcal) root wall of the mesiobuccal canal of mandibular first molars 2 mm below the furcation between group I (long) and group III (short) teeth. The thinnest walls were found in the longest teeth. The deepest concavities in the distal (furcal) walls of the mesial roots were found in the longest roots.

Variability of walking and other daily activities in patients with total knee replacement

Background Three-dimensional motion analysis has provided important information about functional outcome for patients who have undergone total knee replacement, yet many comparisons to control populations are inconclusive. Some of these findings may be explained by variability in patients’ repeated performance, however this has not been previously reported. Therefore the objective of this study was to determine the variability of repeated performance in patients who have undergone total knee replacement during walking and selected activities of daily living using three-dimensional motion analysis. Methods The variability of kinematic and kinetic parameters over six repetitions of walking at comfortable and fast speeds, lunging, stair ascent and descent, squatting and standing up from sitting were measured using motion analysis. Variability was calculated using both the co-efficient of variation, and the group average of the range of data within each subject. Findings During level walking the within-subject difference was less than 3.2° or 0.9 Nm/kg and co-efficients of variation ranged from 2% to 29%. When patients performed other activities of daily living the within-subject difference was up to 8.2° or 1.3 Nm/kg and co-efficients of variation were between 0.5% and 50.5%. Interpretation Although patients walked and performed the activities with reasonable consistency, the variability of their performance appeared to be related to the size of the group mean for each parameter. Comparison of patient groups on parameters with small mean values requires larger sample sizes to prevent intra-subject variability from obscuring differences between groups.

Examining Application of Aggregated and Disaggregated Poisson–Gamma Models Subjected to Low Sample Mean Bias

Two general classes of models have been proposed for modeling crash data: disaggregated (both with and without time trend) and aggregated models. Poisson–gamma models have traditionally been used under both of these model classes. As documented in previous studies, data sets characterized by small sample size and low mean values can significantly affect the performance of Poisson–gamma models, particularly those related to the estimation of the inverse dispersion parameter. Thus, guidance is needed on when to use aggregated models instead of disaggregated models as a function of the sample size and the sample mean value. The objective of this study was to estimate the conditions in which aggregated models (with a higher mean but a smaller sample size) could provide a more reliable estimate of the inverse dispersion parameter than disaggregated models (with a lower sample mean value but a larger sample size) or vice versa. To accomplish this objective, several simulation runs were performed for different values describing the mean, the sample size, and the inverse dispersion parameter. The simulation scenarios represented cases where 3, 5, and 10 years of data were available. To help illustrate the proposed guidance, aggregated and disaggregated models were estimated with crash data collected from four-lane rural highways in Texas. This paper provides guidelines about which model classes are more reliable as a function of the sample mean values, the sample size, and the amount of dispersion observed in the raw data.

Investigation of the effect of the measurement with the abrupt noise and the number of approximated terms in conductional boundary estimation problem

A direct error vector analysis of inverse heat conduction problem is presented to detect the measured noise. Based on the reverse matrix approach that the inverse problem is solved directly in a linear domain, and the error vector is formulated from the difference between the measured temperature and the estimated temperature. There is no prior knowledge on the exact solution while the error vector is constructed. The error vector is used to investigate the consistence of the measured data in the domain and lead to detect the noise data. Furthermore, the proper number of the undetermined variable is able to suggest based on the mean value of the error vector and the value of the condition number of the reverse matrix. In the first example, a test problem with the measurement noise is presented. The estimated result is influent by the noise globally. The result shows that the value of error vector is changed significantly at the coordinate of the measurement noise appeared. In other words, the error vector analysis is able to identify the noise data. In the second example, the proper number of series expansion terms is investigated. From the result, it shows that the number of expansion terms with the small mean value and condition number can better approximate to the unknown condition. It means that the proposed method is able to suggest a proper number of expansion terms when the function of the recovered boundary is unknown.

Variability of subtropical upper tropospheric humidity

Abstract. Analysis of Atmospheric Infrared Sounder (AIRS) measurements for five years shows significant longitudinal variations in the winter subtropical upper tropospheric relative humidity (RH), not only in the climatological mean values but also in the local distributions and temporal variability. The largest climatological mean values occur over the central-eastern Pacific and Atlantic oceans, where there is also large day-to-day variability. In contrast, there are smaller mean values, and smaller variability that occurs at lower frequency, over the Indian and western Pacific oceans. These differences in the distribution and variability of subtropical RH are related to differences in the key transport processes in the different sectors. The large variability and intermittent high and low RH over the central-eastern Pacific and Atlantic oceans are due to intrusions of high potential vorticity air into the subtropics. Intrusions seldom occur over the eastern Indian and western Pacific oceans, and here the subtropical RH is more closely linked to the location and strength of subtropical anticyclones. During northern winter there are eastward propagating features in the subtropical RH in this region that are out of phase with the tropical RH, and are caused by modulation of the subtropical anticyclones by the Madden-Julian Oscillation.

Mandibular dental arch parameters in Down's Syndrome patients with Class I occlusion. (A comparative study).

Background: The aim of this study was to find out the dental arch form for patients with Down's syndrome and to compare the mandibular dental arch parameters of those patients with the corresponding norms, and to gain a correlation between the maxillary and mandibular arches for the Down's syndrome patients from previous study. Subjects and methods: A total sample of 50 patients with Down's syndrome was examined with an age ranged from14-18 years. The mandibular dental arch parameters were compared with another group, control, on student of an intermediate school matching with the age and Angle's classification (Class I). Study models for the maxillary and mandibular arches were constructed, and then dental arch measurements were carried out and evaluated. Results: The mandibular arch parameters for the patients with Down's syndrome showed significantly smaller mean values than the control group for both genders with the males had greater values in inter arch distance and length, with high correlation between the maxillary and mandibular jaws. The wide arch form is the dominated arch form while the flat is the least to appear. Conclusion: The growth pattern of dental arches in Down's syndrome patients is proportionally reduced when compared with those of norms, with a symmetrical configuration. Hence all arch forms are presented with different distribution.

Peripheral fragmentation of 8B nuclei in nuclear emulsion at an energy of 1.2 GeV per nucleon

The results obtained by studying the charge topology of fragments produced in the peripheral dissociation of relativistic 8B nuclei in emulsion are presented. Fifty-five events of the peripheral dissociation of a 8B nucleus in events where there was no production of target-nucleus fragments and mesons (“white stars”) were selected. A leading contribution of the 8B → 7Be + p mode, which has the lowest energy threshold, was revealed on the basis of these events. Information about the branching ratios for dissociation modes characterized by a higher multiplicity was obtained. The dissociation of the 7Be core in 8B bears resemblance to the dissociation of a free 7Be nucleus. The transverse-momentum distributions of fragments originating from the 8B → 7Be + p dissociation mode were obtained. For these distributions, a small mean value of 〈P*T〉 = 52 ± 5 MeV/c in the c.m. frame suggests a low binding energy of the outer proton in the 8B nucleus. An indication of a strong azimuthal correlation of the fragments 7Be and p was found.

North Atlantic Oscillation sensitivity to the El Niño/Southern Oscillation polarity in a large-ensemble simulation

A large ensemble modeling experiment with the Melbourne University General Circulation Model is presented. Thirty 17-year-long independent simulations were performed. All integrations were forced by the same observed sea surface temperatures, obtained from the Atmospheric Model Intercomparison Project II. The simulations were analyzed to assess the sensitivity of the North Atlantic Oscillation (NAO) to the El Nino/Southern Oscillation (ENSO) polarity. The results show signals of the ENSO phases both in the mean strength of the NAO as well as in its internal variability. During the cold ENSO phase, the probability density function of the NAO index presents a small but positive mean value, whereas it is negative during the warm ENSO phase. Also, the NAO variability associated with each ENSO phase shows a different behavior: during the warm phase the probability density function of the NAO index presents a larger variance and suggests a bimodality, whereas no bimodality is suggested in the cold phase.

South China Sea Wind-Wave Characteristics. Part I: Validation of Wavewatch-III Using TOPEX/Poseidon Data

Abstract A full-spectral third-generation ocean wind-wave model, Wavewatch-III, has been implemented in the South China Sea (SCS) for investigating wind-wave characteristics. This model was developed at the Ocean Modeling Branch of the National Centers for Environmental Prediction (NCEP). The NASA QuickSCAT data (0.25° resolution) 2 times daily were used to simulate the wind waves for the entire year of 2000. The significant wave heights from Wavewatch-III are compared to the TOPEX/Poseidon (T/P) significant wave height data over the satellite crossover points in SCS. The model errors of significant wave height have Gaussian-type distribution with a small mean value of 0.02 m (almost no bias). The model errors are comparable to the T/P altimeter accuracy (0.5 m) in the central SCS and are smaller than the T/P altimeter accuracy in the northern and southern SCS, which indicates the capability of Wavewatch-III for SCS wave simulation.

The law of one price: intranational evidence for Canada

Abstract This study investigates the behaviour of intranational prices for 45 specific consumer goods across 25 Canadian cities. It finds positive roles for distance and provincial borders in intercity price disparities. While sizable, the provincial border effect is an order of magnitude smaller than the estimates for the Canada‐U.S. border. A majority of the intercity relative price series are stationary around small mean values, indicating that long‐run price differences are close to zero. The intercity prices converge at rates considerably faster than the consensus estimates for international prices. In fact, half‐lives for intercity price deviations average well under a year. JEL Classification: F15, F31La loi d’un seul prix : résultats intra‐nationaux pour le Canada Ce mémoire examine le comportement des prix intra‐nationaux de 45 biens de consommation spécifiques dans 25 villes canadiennes. Il semble que la distance et les frontières inter‐provinciales ont un impact sur les différentiels de prix entre villes.Même si l’impact des frontières inter‐provinciales est important, il est beaucoupplus petit que l’impact de la frontière Canada‐ U.S. Une majorité des séries de prix relatifs entre villes sont stationnaires autour de petites valeurs moyennes, ce qui suggère que les différences de prix à long terme s’approchent de zéro. Il est clair que les prix entre villes convergent à des taux considérablement plus rapides que ce qu’on observe au niveau international. En fait les déviations de prix entre villes ont une espérance de vie qui en moyenne est de moins d’un an.

Quantitative exposure assessment for the combustion of meat and bone meal derived from specified risk material in the context of BSE in Ireland.

The probability and severity of an adverse event can be analyzed by quantitative exposure assessment (QEA). This methodology was applied to model the human health risks associated with the combustion of specified risk material (SRM) derived meat and bone meal (MBM) in a combustion facility. The identification of MBM and SRM as significant factors in the spread of bovine spongiform encephalopathy (BSE) has resulted in restrictions on their use and movement, and this has led to a requirement for alternative end-uses for these products. A stochastic (Latin Hypercube sampling) simulation model was developed to assess the exposure and hence the risks associated with the use of SRM-derived MBM in a combustion facility. The model simulates the potential infectivity pathways that SRM-derived MBM follows, including its production from animals potentially infected with sub-clinical BSE and subsequent processing of the material with segregation and heat treatments. A failure probability was included to take account of sub-optimal operating conditions. Two scenarios, reflecting the infectivity risk in different animal tissues as defined by the European Commission's scientific steering committee (SSC), were performed with 100,000 iterations of the model. Model results showed that the societal exposure to humans resulting from the combustion of SRM-derived MBM is extremely small (mean values ranging from 7.57 x 10(-6) ID50/year to 8.38 x 10(-5) ID50/year). The resulting societal risks are significantly less than the background societal risk of approximately 2.5 cases of sporadic CJD in Ireland each year. A sensitivity analysis revealed that the species barrier had a large impact on exposure calculations and hence should be the focus of further scientific investigation to reduce our uncertainty about this parameter. The model predicts that material spillage into untreated effluent represents the biggest risk to humans, indicating that efforts for risk mitigation should be focused on reducing the potential for spillage.

Etiologic factors associated with anterior knee pain in distance runners.

The objectives of this study were 1) to examine the differences between a noninjured (C) cohort of runners (N = 70) and runners afflicted with anterior knee pain (AKP) according to selected training, anthropometric, rearfoot motion, ground reaction force, and muscular strength and endurance variables; 2) to explore multivariate relationships among these measures in the well and injured groups; and 3) to develop specific hypotheses concerning risk factors for injury that will later be tested in a prospective clinical study. High speed videography (200 frames x s(-1)), a force platform (500 Hz), and a Cybex II+ isokinetic dynamometer were used to assess rearfoot motion, ground reaction forces, and knee muscular strength and endurance, respectively. A linear discriminant function was performed on each of the five categories of variables and revealed 19 significant (P < or = 0.05) predictors. These variables were then combined and a final discriminant function analysis was performed. Pronation through the first 10% of stance, arch index, shoe mileage, and extension peak torque were the best overall (P < or = 0.05) predictors. The AKP group had smaller mean values on all four significant predictors. With the exception of shoe mileage, which is likely a response to rather than a risk factor for AKP, these results should prove useful to clinicians in identifying runners at risk for anterior knee pain.

Effect of fatty acid saturation in broiler diets on abdominal fat and breast muscle fatty acid composition and susceptibility to lipid oxidation

A total of 600 1-d-old Hybro N broiler chicks were randomly distributed into 24 litter pens and fed from 21 to 52 d of age isocaloric and isonitrogenous diets containing 8% of three different fat sources (tallow, lard or sunflower oil). Dietary treatment produced a significant effect (P < 0.05) in fatty acid composition of the intramuscular neutral lipids among all dietary treatments and for all lipid classes. A similar range of variation was obtained for abdominal fat fatty acid composition. In the intramuscular polar lipid fraction, dietary fat led to a narrow range in the variation of poly- and monounsaturated fatty acid composition, while the concentration of saturated fatty acids was maintained constant in all groups. A wide range in the melting point temperature of abdominal fat was observed (mean values of dietary treatments from 8.49 to 30.91 C), which indicates a major effect of dietary fatty acids on fat consistency. The variation of breast meat oxidation was small (mean values from 7.68 to 9.76 nmol malonaldehyde/mg protein). A dietary fat source rich in linoleic acid produces a marked effect on fat consistency, but only a moderately higher susceptibility to lipid oxidation of meat compared to tallow or lard.

Quantification of the extraction fraction for gadopentetate across breast cancer capillaries.

To quantify the extraction fraction, E, for gadopentetate across tumor capillaries, R3230 adenocarcinomas were implanted in the mammary fat pads of seven rats. The value of E was determined by using a two-compartment tissue model in which the endothelial transfer coefficient, K(PS) (ml x min(-1) x cc(-1) of tissue), was estimated from the model fitted to changes in R1 relaxation time (deltaR1; s(-1)) measured by dynamic three-dimensional spoiled gradient recalled magnetic resonance imaging after injection of 0.1 mmol x kg(-1) of gadopentetate dimeglumine. The plasma flow rate through the tumor capillaries, Fp, (ml x min(-1) x g(-1) of tissue), was independently measured with fluorescent microspheres. E could be calculated by the relationship, E = K(PS)/Fp. The mean E for gadopentetate in the R3230 tumor was 0.197 +/- 0.118 with a range of 0.123-0.454. The relatively small mean value of E for gadopentetate allows a fair approximation of the permeability surface area product by K(PS) in this R3230 tumor model.

Suppression of soliton jitter and interactions by means of dispersion management

Suppression of interaction between solitons in a nearly dispersion-compensated nonlinear optical link built of alternating segments with opposite values of the dispersion is considered analytically in terms of an effective interaction potential generated by exponentially decaying solitons' tails. It is demonstrated that the effective interaction force is that in the homogeneous fiber divided by a factor equal to a ratio of the actual value of the dispersion to its small mean value. An important result is obtained for the soliton jitter in a similar model, in which, however, the mean dispersion slowly decreases ∼1/ z, rather than being constant. By means of the Fokker-Planck equation for the soliton's random walk, it is shown analytically that this mode of the dispersion management provides a strong suppression of the jitter, so that the mean-square random displacement of the soliton grows only as z, in contrast with the Gordon-Haus growth law z 3. A simple relation between parameters of the corresponding dispersion-management map, providing the strongest jitter suppression, is found.